Intravascular Ultrasound Evaluation of Interwoven Nitinol Stents at Implant

Frank J Arena

Purpose: To evaluate the performance of Interwoven Nitinol Stents placed in the Superficial Femoral and Popliteal arteries using Intravascular Ultrasound (IVUS). Methods: 37 stented segments in 34 patients whose procedures involved using IVUS during their peripheral angioplasties were retrospectively examined. Twenty seven 5 mm stented segments and ten 6 mm segments were measured. The IVUS study showing each stented segment was measured at ten approximately equal distances. At each of these points the size of the lumen was measured. The area inside the stents, as well as the minimum and maximum diameters across the stent were determined. The minimal area from each segment was also obtained. These areas were averaged and the stent expansion ratio (SER), average in stent area/maximal stent area was determined for each segment. The minimum and maximum diameters in each segment were also determined and the Radial Stent Symmetry Index (RSSI), minimum/maximum stent diameter was calculated for each segment. Results: The 5 mm Interwoven nitinol stent group achieved an SER of 96.5%. The 6 mm group achieved an SER of 87.83%. The minimal SER measurement among the 5 mm stents averaged 76.67% and the 6 mm stents 65.71%. The RSSI in the 5 mm segments were 90.49%, while the 6 mm group was 88.80%. Conclusions: Interwoven Nitinol stents perform well at implant with consistent deployment areas across multiple stent sizes when used in the SFA and Popliteal arteries. RSSI calculations were generally consistent with a relatively round stent deployment.